Combustion chamber fluid inlet construction



Jan. 29, 1963 w. SHUTTS 3,075,352

COMBUSTION CHAMBER FLUID INLET CONSTRUCTION Filed Nov. 28, 1958 2 Sheets-Sheet l IN VEN TOR.

ATTORNEY 2 Sheets-Sheet 2 Jan. 29, 1963 w. SHUTTS COMBUSTION CHAMBER FLUID INLET CONSTRUCTION Filed Nov. 28, 1958 5" y WWW Q a y V T 0 w. S M ,W W h #7 Wu Ill F4. .1 w I U @a s we WW M 9 9, @fio 0 mo 6% mm W W Q as 9 QD.ID.L.\Q 6/ o 6 AT TOP/V15 Y United States Patent Delaware Filed Nov. 28, 1958, Ser. No. 776,928 Claims. (Cl. 6039.65)

This invention relates to a combustion apparatus.

More specifically, this invention relates to the particular construction of a combustion chamber in a gas turbine engine, the construction being such as to reduce the time necessary to provide a combustible mixture of fuel and air therein, thereby moving the flame front closer to the forward section of the combustion chamber and permitting the use of a shorter combustion can. This therefore reduces the cost of the engine, the weight, and drag, therefore improving the engine.

This invention provides the dome of the combustion can with a stepped cone construction, the overall contour of the stepped cone approximately paralleling the fuel spray cone path. Additionally, the steps of the cone are provided with air inlets at right angles to each other so that small local air jets or vortices are provided to rapidly mix the air and fuel vapor thereby quickly pro ducing a combustible mixture therein.

Therefore, an object of this invention is to provide a combustion can construction such that the proper fuelair mixture is obtained as quickly as possible, therefore moving the flame front as close as possible to the forward end of the combustion can, permitting a reduction in length of the can.

A further object of the invention is to provide better mixing of the air with the fuel discharged into a combustion can from the fuel nozzle by providing a multiplicity of air jets producing minute individual vortices quickly intermixing the fuel vapor with the air.

It is a still further object of this invention to provide a combustion can dome structure such that the primary air intermixing with the fuel spray is evenly intermixed by providing air introduction means presenting the air to the primary inlets free from the effects of ram air velocity.

Other features, advantages and objects will become apparent by reference to the detailed description of the invention and to the drawings wherein there is shown the preferred embodiments of this invention.

In the drawings:

FIGURE 1 is a side elevational view of a gas turbine engine embodying this invention with parts broken away and sectioned,

FIGURE 2 is a cross-sectional view through the combustion section on a plane indicated by the lines 2-2 of FIGURE 1,

FIGURE 3 is an enlarged longitudinal cross-section view of the dome on a plane indicated by the lines 33-3 of FIGURE 2,

FIGURE 4 is an end view with parts broken away of the dome of FIGURE 3 on a plane indicated by the lines 4-4 of FIGURE 3.

Referring now to the drawings and more particularly to FIGURES l and 2, there is shown therein schematically a portion of a gas turbine engine having a compressor section 12 of the axial flow type, a diffuser section 14, a combustion section 16 and a turbine section 18 (only partially shown). The combustion section consists of a cannular chamber 20 having an outer wall defined by the engine casing 22 and an inner wall defined by the shroud 24. Positioned within and axially spaced circumferentially around the combustion chamber are a number of combustion cans 26 having the usual igniter plugs 28 inserted therein, the cans being connected-to each other by crossover tubes 30 for the propagation of the flame therebetween. As is conventional, only one or two of the igniter plugs 28 need be live, the remaining plugs being dummy plugs.

The combustion can is generally of a cylindrical shape as shown, with a convergent transition section 32 at one end cooperating with the turbine inlet vanes of the turbine section 18, and a dome end 34 connected to and supported by a fuel nozzle 36' having a connection 38 to a fuel supply line adjacent the diffuser section 14. The cans are generally constructed of overlapping anuu lar sections 40 with spacer members 42 therebetween for air cooling purposes, sections 40 and members 42 being welded together at their corrugated edges (not shown). Dilution air holes 44 and reinforcing members 46 are also provided. The construction of the cans as so far described is known and the details thereof are immaterial to the present invention, and therefore no further de tails will be described. The construction of the dome 34 in a manner to permit entry of primary air therethrough to intermix with the fuel spray, which is the subject of this invention, will now be described.

Referring now more in detail to FIGURES 3 and 4 showing detailed cross-sectional and end views of the subject combustion can, it will be seen that the combustion can dome 34 has a flat or blunt nose dome 48 closing the upstream end of the combustion can. Centrally thereof at the axis of the can is an annular aperture or opening 50 for the insertion therein of the fuel nozzle 3-6 inserted into the dome of the combustion can for supporting the can. The can is provided with a boss 54 inserted through the longitudinal wall of the can as shown for receiving therein a conventional igniter plug 56 fixed to the engine casing 22 and extending towards the center of the can as shown. Fixedly secured to the after part of the can is the stepped cone dome 58 forming the subject of this invention. The stepped cone constitutes an inner annular wall of the combustion can and its general overall outline substantially parallels the conventional cone-shaped fuel spray pattern imposed on the fuel by the fuel nozzle 36 to fill as much of the diameter of the dome as possible. The stepped cone 53 has a wavy or zigzag outline or periphery as shown comprising a single piece of sheet metal corrugated or bent in steps to comprise a number of axially extending portions 60 alternated with radially extending portions 62, the finished cone appearing as a stepped shape. As shown, each of the axial portions 69 is provided with a number of circumferentially spaced holes or apertures 64 through which the air is admitted with a jet effect producing small scale turbulent areas on the aft side of the cone. The radial portions 62 are likewise provided with a number of circumferentially and equally spaced apertures or openings 66 for the admission of gas therethrough. The particular number and size of the apertures at each step are chosen so as to produce the greatest number of vortices possible to produce the maximum mixing of the fuel and air, the size of the apertures increasing with an increase in the radial distance from the axis because of the need for a greater volume of air to properly mix with the greater volume of fuel spray. The number of radial and axial apertures at each step of the dome are equal, while the number of apertures at different steps is different. It is to be noted by reference to the drawings that the axial and radial apertures 64 and 66' at each step of the dome are otfset laterally or staggered circumferentially with respect to each other so that the radial and axial jets of air will pass or cross over each other to set up a swirling action between the two to produce a great number of small vortices completely filling the areas immediately adjacent the fuel spray cone with small side turbulences so that better and quicker mixing of the fuel with the air is accomplished.

A number of circumferentially spaced bafiie members 63 are secured to the inner dome wall 58 as shown in FIGURE 4 to act'as gas or air deflectors imparting a swirl to the air to cause the air to continually wash the inside surface of the can immediately adjacent the baffl-es thereby cooling the can at this portion. Because of the apertured stepped cone construction producing a quicker combustible mixture of the fuel and air, the flame front, which in previous combustion can constructions heid a position at about the bafiie plates, now moves forward closer to the dome Wall.

The compressor discharge air as delivered to the diffuser section 14 is introduced to the stepped cone dome waii through the blunt end 48 of the combustion can by way of a number of spacedapertures or holes 7' The rimary purpose of these holes 70 is for distributing the .air .therethrough into contact with the inner stepped cone dome 58 so that the air entering through the apertures 54 and 66 in the dome will have a more uniform pressure and be free from the impact pressure and other uneven velocity efiects of the ram air. The air entering through the openings '70 thus fills the chamber 72, which in eifect is a plenum chamber, and is evenly distributed over the entire outer surface of the stepped dome 58.

The operation of the gas flow through the combustion can is therefore as follows. The air discharged from the compressor outlet '74 is delivered to the combustion can dome 34 with great ram velocity and enters through holes 76 in the combustion can dome end 43 to fill the chamber 72. Chamber 72 causes the air to be evenly distributed to the apertures 64 and 56, that is, the air entering through the holes 70 breaks up the mass of ram air so that these and other efiects are not relayed into the apertures 64 and 66. The compressor discharge air therefore enters the holes 64 and 66 creating a great number of small local vortices or turbulences adjacent eachof the holes, the staggering of the axial and radial holes of each step imparting the swirl to the jets of air by the one crossing over the other. At the same time, the fuel is being fed through the fuel nozzle 36 and sprayed into the combustion can in substantially a cone shape path, the path approximately paralleling the overall average periphery of the inner wall or dome 58. The individual turbulent air swirls created on the downstream side of the holes 64 and 66 therefore strike the fuel spray immediately mixing therewith to quickly produce a combustible mixture which can be immediately ignited to cause the flame front '73 to hold as close as possible to the front of the combustion can. By movement of the flame front closer to the combustion can, the length of the combustion can can be decreased thereby decreasing the weight, cost and drag of the engine.

Therefore, it will be seen that this invention provides a combustion can construction that reduces the time necessary to provide the proper fuel-air mixture for combustion while increasing the efficiency and reducing the overall length of the combustion can. While the combustion can dome has been shown in these figures in its preferred form, it will be clear to those skilled in the art that many modifications can be made therefrom without departing from the scope of the invention.

:1 claim:

1. A combustion apparatus comprising a longitudinally extending annular gas passage, a substantially cylindrical combustion chamber therein, said member having an outlet at one end for combustion products, a longitudinally extending dome means closing the other end of said member, a fuel nozzle projecting fuel therefrom, an aperture in said member centrally thereof for the insertion therein of said fuel nozzle, said fuel nozzle distributing said fuel in .a substantially cone-shaped spray upon the passage of fiel through said fuel nozzle, said dome means having an annular wall extending radially from said aperture and a longitudinal annular wall connected to the end wall at its outer edges, said end Wall having a plurality of openings therein for the admission of gas therethrough directly into said chamber, an innor annular corrugated wall secured to portions of the end and longitudinal walls of said member, the overall shape of said inner wall substantially paralleling the cone-shape of said fuel spra said inner wall comprising .a plurality of annular axially and radially extending portions axially alternated with each other and joined at their adjacent edges, each of said adjacent portions having a plurality of circumferentially spaced apertures therein, each of the axially adjacent apertures being substantially at right angles to the other for the admission of gas thereth-rough in a plurality of spaced jet paths in different planes, the spacing of said paths imparting a swirling motion to said gas adjacent each of said apertures, the admission of gas through the apertures in said outer wall distributing said gas evenly to the apertures in said inner Wail, the admission of gas through the apertures in said inner wall providing eflicient atomization of the fuel spray therein by the creation of local vortices adjacent said apertures due to said swirl, the apertures in the radial portions of said inner wall being offset circumferentially in a staggered manner with respect to the apertures in the adjacent axial portions of said inner wall to impart said swirling motion to the gas admitted therethrough by the passage of one gas jet over another.

2. A combustion chamber for burning fuel therein having a perforated fuel and gas inlet wall portion, means projecting fuel through said wall portion in a spray pattern generally parallel to the overall shape of said wall portion and spaced from the wall portion, said wall portion comprising a plurality of successively arranged strips of substantially equal width at an angle to each other and joined at their adjacent edges to provide a step-like corrugated aspect having substantially equally proportioned corrugations, each of said strip-s having a row of perforations for the admission of gas therethrough in jet streams directly into said chamber and at substantially equal angles to the line of projection of said fuel, the perforations of adjacent strips being misaligned with respect to each other so that the jets of gas at angles to each other pass each other Without direct impingement thereby setting up local turbulences in the area of mixture of the fuel and gas promoting intimate mixture of the fuel and gas.

3. A combustion chamber for burning fuel therein having a perforated fuel and gas inlet Wall portion, means projecting fuel through said wall portion in a spray pattern generally parallel to the overall shape of the wall portion and spaced therefrom, said wall portion comprising a plurality of successively arranged strips approximately at right angles to each other and joined at their adjacent edges to provide a step-like corrugated aspect, each of said strips having a row of perforations for the admission of gas therethrough in jet streams at right angles to each other and directly into said chamber and proximate to said fuel at substantially equal angles to the peripheral line defining said fuel spray pattern, the perforations of adjacent strips being staggered lengthwise of the strips so that the jets of gas at right angles to each other pass each other without direct impingement thereby setting up local turbulences in the area of mixture of the fuel and gas promoting intimate mixture between the fuel and gas.

4. A combustion chamber having a perforated pyramidal-shaped gas and fuel inlet wall portion, said wall portion consisting of a tier of cylindrical strips of substantially equal axial width with successive strips having diam eters increased by substantially equal increments, each of said strips having a row of gas jet orifices therein, said strips being joined at adjacent edges by an annular radially extending strip of substantially uniform Width secured thereto having a similar row of gas jet orifices, the mutually adjacent strips together providing orifices at right angles to each other, the axially adjacent orifices of said strips at right angles to each other being staggered circum. ferentially with respect to each other so that the gas jets cross each other without direct impingement and pass directly into said chamber in a direction normal to said strips upon passage of the gas through said orifices, means projecting fuel through said wall portion into said chamber in a spray pattern generally parallel to and spaced from the overall shape of said wall portion and proximate to said gas jets, the cross jets setting up a plurality of local turbulences in said zone promoting intimate mixture of said fuel and gas.

5. A combustion chamber comprising a substantially cylindrical member for burning fuel therein, said member having a dome-shaped fuel and gas inlet at one end and an outlet for combustion products at its other end, the outer periphery of said dome comprising an axially continuously corrugated annular surface having along the axial extent of said surface a continuous plurality of axially adjacent apertures therein each at an angle with respect to the adjacent one for the admission of gas therethrough directly into said chamber in paths at angles to each other, means for supplying fuel to said member in paths substantially parallel to the overall shape of said surface, said apertures being staggered circumferentially with respect to the apertures at angles to each other, whereby the admission of gas through said apertures creates individual local gas paths passing by each other imparting a swirling motion thereto to atomize the fuel in contact therewith.

References Cited in the file of this patent UNITED STATES PATENTS 2,573,694 De Zubay et al. Nov. 6, 1951 2,616,257 Mock Nov. 4, 1952 2,687,010 Ellis Aug. 24, 1954 2,765,621 Poulston Oct. 9, 1956 2,775,094 Buckland et al. Dec. 25, 1956 2,930,194 Perkins Mar. 29, 1960 UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No" 3,075,352 January 29, 1963 Leroy W; Shutts I It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should .read as corrected below.

a Column 6, line 6, for "to each other" read thereto line 9 for ."thereto" read to each other a Signed and sealed this 10th day of September 1963.,

(SEAL) Attest:

DAVID L. LADD Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. A COMBUSTION APPARATUS COMPRISING A LONGITUDINALLY EXTENDING ANNULAR GAS PASSAGE, A SUBSTANTIALLY CYLINDRICAL COMBUSTION CHAMBER THEREIN, SAID MEMBER HAVING AN OUTLET AT ONE END FOR COMBUSTION PRODUCTS, A LONGITUDINALLY EXTENDING DOME MEANS CLOSING THE OTHER END OF SAID MEMBER, A FUEL NOZZLE PROJECTING FUEL THEREFROM, AN APERTURE IN SAID MEMBER CENTRALLY THEREOF FOR THE INSERTION THEREIN OF SAID FUEL NOZZLE, SAID FUEL NOZZLE DISTRIBUTING SAID FUEL IN A SUBSTANTIALLY CONE-SHAPED SPRAY UPON THE PASSAGE OF FUEL THROUGH SAID FUEL NOZZLE, SAID DOME MEANS HAVING AN ANNULAR WALL EXTENDING RADIALLY FROM SAID APERTURE AND A LONGITUDINAL ANNULAR WALL CONNECTED TO THE END WALL AT ITS OUTER EDGES, SAID END WALL HAVING A PLURALITY OF OPENINGS THEREIN FOR THE ADMISSION OF GAS THERETHROUGH DIRECTLY INTO SAID CHAMBER, AN INNER ANNULAR CORRUGATED WALL SECURED TO PORTIONS OF THE END AND LONGITUDINAL WALLS OF SAID MEMBER, THE OVERALL SHAPE OF SAID INNER WALL SUBSTANTIALLY PARALLELING THE CONE-SHAPE OF SAID FUEL SPRAY, SAID INNER WALL COMPRISING A PLURALITY OF ANNULAR AXIALLY AND RADIALLY EXTENDING PORTIONS AXIALLY ALTERNATED WITH EACH OTHER AND JOINED AT THEIR ADJACENT EDGES, EACH OF SAID ADJACENT PORTIONS HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED APERTURES THEREIN, EACH OF THE AXIALLY ADJACENT APERTURES BEING SUBSTANTIALLY AT RIGHT ANGLES TO THE OTHER FOR THE ADMISSION OF GAS THERETHROUGH IN A PLURALITY OF SPACED JET PATHS IN DIFFERENT PLANES, THE SPACING OF SAID PATHS IMPARTING A SWIRLING MOTION TO SAID GAS ADJACENT EACH OF SAID APERTURES, THE ADMISSION OF GAS THROUGH THE APERTURES IN SAID OUTER WALL DISTRIBUTING SAID GAS EVENLY TO THE APERTURES IN SAID INNER WALL, THE ADMISSION OF GAS THROUGH THE APERTURES IN SAID INNER WALL PROVIDING EFFICIENT ATOMIZATION OF THE FUEL SPRAY THEREIN BY THE CREATION OF LOCAL VORTICES ADJACENT SAID APERTURES DUE TO SAID SWIRL, THE APERTURES IN THE RADIAL PORTIONS OF SAID INNER WALL BEING OFFSET CIRCUMFERENTIALLY IN A STAGGERED MANNER WITH RESPECT TO THE APERTURES IN THE ADJACENT AXIAL PORTIONS OF SAID INNER WALL TO IMPART SAID SWIRLING MOTION TO THE GAS ADMITTED THERETHROUGH BY THE PASSAGE OF ONE GAS JET OVER ANOTHER. 